Problem: Ben starts counting at 47, and he counts by threes. If 47 is the 1st number that Ben counts. what is the 9th number that he counts?
Solution: What is the first number that he counts? $47$ What is the second number that he counts? $\begin{align*}&47 + 3 \\ &= 50\end{align*}$ What is the third number that he counts? $\begin{align*}&47 + 3 + 3 \\ &= 47 + (2 \times 3) \\ &= 53\end{align*}$ What is the 9th number that he counts? $\begin{align*}&47 + (8\times3) \\ &= 47 + 24 \\ &= 71\end{align*}$